


Sebastian meets his new little Boy

by Casmonster1



Category: Sherlock (TV)
Genre: Daddy Seb, Diapers, Little Jim, M/M, first time Daddy Sebastian is unsure
Language: English
Status: Completed
Published: 2016-10-19
Updated: 2017-01-31
Packaged: 2018-08-23 08:46:23
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 2,861
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8321467
Author URL: https://archiveofourown.org/users/Casmonster1/pseuds/Casmonster1
Summary: Sebastian discovers a secret that Jim has been hiding. Still a bit unsure, but he takes it upon himself to assume a new role in their relationship.





	1. Chapter 1

Sebastian worked on the lock, he had not been told to pick the lock, but it would be just like Jim to test him without saying anything. This was the only room he had yet to see in anyway so the curiosity was there.

But given his skills were in combat, it took longer to break and enter into the room than he wanted to admit. He could hear movement beyond the door.

Was Boss in there?

Sebastian finally got the door unlocked, pushing it open, what he saw inside made his brain short circuit.  
\-----------  
Jim could feel the antsy feeling inside, he was so relieved to have a moment to himself. Finally he was able to let his Little side out instead of caging it down like he had for what felt like years. He fingered his CD's, picking one of his favorites. He knew it would be one of the last straws to pushing his Little Jim to the surface. 

He liked to hide in here, the castle themed nursery made the transition easier, he moved to strip off his suddenly bulky grown up clothes, taking out one of the onesies from the dresser, the stars and candy making him giggle as he began to dig through the toy chest for Berry.

The bear was purple with stars and a heart nose, Jim loved it, but he wished he didn't have to hide his friend away. Jim grabbed his blue blankie, crawling to the couch, holding Berry close as he sniffled, hiding under the blanket. He was lonely.

\-------  
Sebastian blinked, he couldn't believe what he was seeing, his Boss, the most feared man in London was-is- what... This is not in my job description, but still the Sniper couldn't make himself move or speak, his body not connecting with his brain. 

Jimmy heard the door open, his eyes peeking out from under the blue blankie, people weren't supposed to find his room... he was in trouble. "Sebby...."

Sebastian was still trying to decide if he should speak or walk away when he heard the sweet little voice. No, don't think of him as cute, this was obviously a private thing, why else would he lock the door? "Yes.... sir?"

Jimmy looked up again, his eyes wide, he reached out toward the man, his lip trembling. "H-hold?"

Sebastian sighed, oh joy.... he's going to cry. Sebastian stayed rooted to the spot. "No, that is not why I'm here. You can take care of yourself."

Jim whimpered, he had been alone so long... He sucked on Berry's ear as tears started rolling down his face. 

Sebastian should've known it wasn't going to be a normal gig when he signed up, but... this was not what he had expected at all, sighing in acceptance the Sniper walked over to the couch, picking up his Boss. "Hush now, no need for tears."

Jim leaned into Sebastian, nuzzling against his chest. Safe, warm. "Daddy."

Sebastian felt his body freeze, well this was a development. "Yes, baby. Daddy has you."

What if this bit him in the ass? but as he looked down at Jim, for some reason, Sebastian couldn't think of that right now, considering the baby had stopped crying. 

Sebastian rocked Jim as he looked around the room, it looked like a normal nursery, only adult sized. He could see all the small touches that were clearly Jim's handiwork, which meant he wasn't joking around. Sebastian would need to do as much research as he could find in his spare time to know how to care for Jimmy if he was feeling little, but what happens when he becomes big again?


	2. His First Bottle

**Summary for the Chapter:**

> Sebastian makes a bottle for Jimmy after he wakes up.

Sebastian wasn't sure how long he sat there, listening to the deep breathing of the man curled up in his lap, which was still confusing beyond belief, his Boss.....

Not that this confused him about his respect for James, because Jim would still kill you as soon as blink. Given his attitude at times, even if at present he was sucking on a teddy bear in footsie pjs.

Being hired to take care or watch over someone meant taking care of all of his needs, Sebastian couldn't say no, even if this was making his head spin a little. He should move Jimmy to the crib he saw in the corner, given there wasn't a big bed in here that must be what he preferred when Little. Sebastian had a feeling Jim would be most comfortable in his own space.

Sebastian was careful as he stood up, holding the Irishman to his chest, if Jimmy got too jostled, he'd wake up and Seb didn't want the crying to start again, it would for sure cause a headache. He needed to go digest this and sitting here wasn't helping anything.

With a major change like this, Seb needed facts, what if he hurt Jimmy somehow? That would be bad, possibly fatal, he couldn't take a chance. 

Jim rolled over to look up at Daddy, reaching up with a yawn when he had been moved from the strong chest he had been pillowed on.

Sebastian reached down to rub Jimmy on his tummy. "Sh, Daddy will be right back, go night night, sweetie."Seb may be hard, but he wasn't horrible, not when he was speaking to a baby. Jimmy was sweet and soft, how could you be mean? Even a little, except Sebastian had been mean.... He had told Jim to take care of himself.. As Sebastian gazed down at him now, he had been wrong. That was a mistake to say those things, even if Jim had been thinking like his Boss at the time, It was Seb's job to look out and protect him no matter what, even if it got him hurt. 

Sebastian slowly moved out of the room, shutting off the light, watching a nightlight click on along with a mobile. They must be on sensors, Sebastian smiled, Jim had thought of everything... He really was a genius. He had left the door open a crack in case Jimmy woke up and needed anything.

As he walked down the hall, his head racing with thoughts. How had he gotten into this? Why hadn't he made Jim come back to himself, any weakness can be exploited, Jim knew that and yet... He was also a Little. 

Sebastian walked down the hall, stopping in the living room. Why.... okay, reading. Sebastian sighed, it was going to be a long few hours, but he moved to the computer, starting a search.

It took only a short time for Sebastian to read up on the normal behavior for a Little and how they ranged in ages... but Jimmy was different, what if he threw a tantrum? Yes Seb could handle the cuddling, but could he take care of Jimmy if he was crying and yelling? Yes, Sebastian nodded as he clicked to the next page.

He quickly skimmed over the more... explicit aspects that people dabbled in, not to say that he wasn't attracted to Jim, but it felt wrong when he was Little to take advantage of him in that way.

Sebastian concentrated more on the 'new Daddy' page that one of the sites had posted. Going over each new article...closeness was key depending on how little your baby is, which Seb had already seen with how Jim acted being placed in his crib. 

Sebastian closed the laptop, he'd finish later. He bit back a groan as he heard the crying again... Jimmy must be very small if that is his main form of communication. Sebastian stood and walked down the short hallway, going into the nursery and picking the baby up, bouncing him. "Sh, Sh, hey. Nothing to worry about, buddy, Daddy is here."

Jim cried, snot running down his nose as he cuddled against daddy. He was gonna get Jimmy... Bad man.. 

Sebastian rocked Jim, grabbing a tissue to wipe his nose as he walked out of the nursery, moving down the hallway and taking a right to go to the kitchen. "Let daddy fix a bottle for you." Sebastian had grabbed one from the nursery, he understood why everything wasn't placed in the correct spots through the house, but Jim hid his secrets well.

Jim held tight to Daddy's shirt, he didn't want to be taken away. His cries subsiding to hiccups. 

Sebastian fumbled with the bottle as he tried to balance Jim and making the bottle, he ended up spilling the formula, glancing between Jimmy and the bottle. This wasn't working... But Jimmy wasn't going to let up. 

Sebastian sat the scoop down, he had seen a bouncer in the second living room, the one he could tell was hardly used, that was probably why Jim kept it there. Sebastian bounced Jimmy as he walked upstairs,. "Daddy has a surprise, Baby boy."

Jimmy looked up at Daddy. He didn't know about the bad man, but a surprise for him?

Sebastian smiled as he carried Jimmy into the smaller living room, grabbing the purple bouncer. Carrying it in one hand downstairs back to the kitchen, he sat it down and strapped Jimmy in. "Now You can still see Daddy while he makes something yummy."

Sebastian finished the bottle, picking up Jimmy to feed him, cradling him with his head against his shoulder, sitting down on the couch. "Every thing is fine, no more scary."

Jimmy latched onto the bottle, sucking as he leaned against Daddy, his eyes falling closed as he fell asleep.


	3. A Unexpected Problem

**Summary for the Chapter:**

> Jimmy is settling in well, but something is arriving to destroy their fun times.

Sebastian laid Jim down on the couch, wrapping him in a blanket tightly, he kept hoping Jim would come out of this, something had to snap him out of this mindset, right? Sebastian picked up the bottle, carrying it to the kitchen, yes this wasn't in his job description, but he was very proud to say he was adjusting well. As he washed the bottle.

After he finished cleaning up the kitchen, Sebastian moved back to the living room, sitting down to watch over Jimmy while he slept. All in all... this was going well, no tantrums yet and Sebastian hadn't needed to change a diaper, but he had a feeling that would be in his future. 

Sebastian looked up from his book when he heard rustling. Jimmy was stirring. "Someone's awake, i see."

Jimmy fought against the blanket, small whimpers coming from him as he got frustrated at not being able to move.

okay, not again. Sebastian moved to unfold the blanket and pick him up. The faster he learned the more headaches he could avoid. He smiled down at Jimmy, bouncing him as they walked. "You could've told me, you know."

Jim only giggled softly as he squirmed, farting as he used his diaper. 

Oh... Sebastian walked the rest of the way to the nursery, laying Jimmy on the changing table. "Okay, this is fine... I can do this, it's not weird or not more so than anything else I've been through. "

After that small pep talk, Sebastian moved to the diapers on the top shelf, grabbing the powder and wipes. Still trying to get himself ready for this. Before undoing the onsie, tickling Jimmy's tummy. His eyes easily drawn to the knife scar on the baby's shoulder.

It was easy to forget Jim wasn't invincible. Sebastian took off the soiled diaper, throwing it in the bin and cleaning him with a wipe, thoroughly but carefully, sprinkling a good amount of powder on before carefully lifting his lower half to slide the new diaper underneath and tape it up, replacing the onsie before picking Jimmy up. 

"All better, buddy. Let's go see what toys you have." Sebastian moved to the toy chest, setting Jimmy down before sitting beside him. Sebastian pulled out a bag of soft blocks. "wanna build a castle with Daddy?"

Jim giggled happily as Daddy picked him up, reaching out for the blocks. 

Sebastian sat the bag down, before slowly lowering Jimmy down to lay on his stomach, dumping the blocks out in front of the baby. He knew they were safe to play with since they were soft.

\--------

Jacob watched from the shadows, all this time I believed he was some big, scary criminal, but if what I had been observing was real, my assumptions have all been wrong.

James Moriarty, the mastermind of the underworld.... was acting like a baby, this had to be a trick. Jacob moved around the trees, getting closer to the window to get a better look. Yes, that would make it easier to abduct him, breaking the great James Moriarty wouldn't be as fun though, if the fight was out of him already. 

Jacob climbed down out of the trees, as far as he knew there was only the one guard. Easy to take out, you'd assume a man as powerful as Jim would be well protected, but once again it worked in the thief's favor.

He easily got the door open, stepping inside. Not two seconds later the alarms began to blare. 

Now the fun began.


	4. Chapter 4

Sebastian looks up from the blocks, this he knew how to handle. He swiftly scooped up Jimmy. 

Jim put his hands over his ears, loud.. crying loudly as the noise hurt his ears. 

Sebastian moved to the nursery, Jim must've put some safety feature in there, at least he knew Jimmy would be safe.. Who could have gotten near the house? Close enough to get inside? "Stay here, sweetie. Let Daddy take care of the scary noise."

Sebastian wasn't even sure if Jimmy heard him, his crying was so loud. Sebastian looked around the room, grabbing a blanket to lay it over the boy, his eyes landing on a switch by the door. James obviously hadn't thought anyone would get this close, but the switch was labeled 'security' Sebastian flipped it, but also locked the door on his way out, slipping the key in his pocket. 

Jacob moved silently though the house, checking the corners as he walked, they had ran fast, but where was his target? James seemed to have disappeared.

"You picked the wrong house, jackass."

Sebastian quickly leveled his gun at the intruder not that he ever gave chances for his targets to make a sound, but this piece of scum had gotten inside, not many people could do that. 

"Where's your boss? he's the one I want not some lap dog." 

Lap dog you say? Sebastian fired off a shot, the silencer and loud sirens blocking the noise. He was having a relaxing time, finally getting into some kind of swing with this new arrangement, now here he was with a gun in his hand. "next one hits your heart. Get out of this house."

Jacob smirked, taking several steps forward. "He's got you so trained."

Sebastian took aim, letting off two rounds as they hit the man in his head. "Lap dog, my ass. "

Now that left the mess of cleaning up the body..

Along with shutting off that damn alarm. Sebastian moved around the growing blood spot and made his way to the security room, shutting off the alarm, which finally left the house quiet. He made his way back to the nursery, happy to find the door still locked. 

He moved quickly, first picking up the body to carry it outside, he could deal with it later or just let the body rot under a shallow grave... that was always appealing. 

Sebastian quickly cleaned up the blood, that man deserved it, calling him a lap dog. Sebastian slowly went through the house to check all points of entrance, he couldn't risk someone getting to Jim, not when he was like this... 

Jim relaxed as the noises went away, but where dada? He ewnt away.... Jim moved the blanket, not wanting to be covered, shaking as he heard the door open. Bad man..... 

"Hush, It's only Daddy." Sebastian reached down to pick Jim up, is heart broke with every whimper. "At least you're safe, Jimmy. I don't know what I would have done."

Jimmy looked up at Daddy, his brown eyes wide, tears still falling, he reached up with a fist and rubbed his eyes. 

"No tears, baby. No scary people are going to get you." Sebsatian bounced him. 

Jim blinked, sudden recognition filling his eyes. "What happened?" 

Sebastian was incredibly proud of his arms, they hadn't given out. He's back, Boss and I didn't drop him. Jim was himself again or the other version of himself. And....... I'm still holding him. Sebastian cleared his thraot, setting Jim down. "We had an issue, sir. You were , uh. . Indisposed."

Indisposed...... Jim tried to not show his shock as he looked down, I'm...... well fuck, this is JUST great. He felt the shaking that came after he returned to his Big self, pushing past Sebastian into the living room. "I am going to my office, do not disturb me for anything."

Sebastian nodded. "Of course, Sir. I'll go double check security."

Jim smiled, thank you, Sebastian, for everything. "Good boy, Tiger."

Sebastian turned without saying anything, same old, same old.... except now they had to ahve a talk, because this changed things.


End file.
